消失的内容 c++ 写入文件

问：

每当我在重新运行代码后将数据写入文件时，文件的内容都会消失

#include <iostream>
#include <fstream>

using namespace std;


int main(){
    string username = "";
    string path = "/Users/kishorejyothi/Desktop/C++/practice/list_usernames.txt";
    ofstream file(path);

    if(file.fail()){
        cerr << "Failed process";
        exit(1);
    }

    cout << "Enter a username: ";
    cin >> username;

    string full_username = username.append("@Abhinav.com");


    if(username.empty()){
        cout << "You didn't enter your username";
    }
    else{
        cout << "Thanks for entering your preferred username." << endl;
        cout << "Your username is now " << full_username;
    }
    file << username << endl;

    file.close();
}

我正在检查该文件以将用户名写入单独的代码行。